Messages in this thread | | | From | "Zeng Yu" <> | Subject | Re: Ramdisk Bug? | Date | Thu, 28 Jun 2001 22:21:15 +0800 |
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> > I think find a ramdisk bug of 2.4.4 kernel -- ramdisk > > use both buffers and cached mem of the same size, thus > > double the mem use. > > mke2fs -m0 /dev/ram1 > > mount /dev/ram1 /mnt > > dd if=/dev/zero of=/mnt/data bs=1k count=110000 > > cat /proc/meminfo will see that both buffers and > > cached mem increase about 110M of size. More worse, > > the cached mem won't be released untile the ramdisk > > be umounted. I attach the meminfo and slabinfo before > > the "more worse" part is the only thing which is wrong. The fact cache > also grows to 110M is expected and it won't change. With the > blkdev-pagecache patch the cache will grow to 220M and it will shrink to > 110M if you are low on memory (buffer cache will only be allocated for > the superblock and inode metadata with ext2).
broken, clean 2.4.4 kernel with blkdev-pagecache-1 and o_direct-5 patch mke2fs /dev/ram0; mount /dev/ram0 /mnt VFS:can't find an ext2 filesystem on dev ramdisk(1,0) mount:wrong fs type, bad option, bad superblock on /dev/ram0 ... I miss something?
BTW, I noticed that the blkdev-pagecache had been submitted early in 2.4.5 pre1, but not included in 2.4.5 final, 2.4.5 still has the bug -- can't release mem unless the ramdisk unmounted. Would this be considered not a problem or just a bearable side-effect for some elegant designs?
> use ramfs if you want zero ram duplication and you don't care about the > physical representation on disk of your data in cache. ramfs's src code inode.c says it not for general use, so not try and I can't find any docs about how to use it.
> Try this patch to fix the "more worst part" (beware totally untested). seems works. will do more tests though. thanks!
regard,
Zeng Yu
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